Comprehensive Voltage Control Strategy for New Energy Isolated Island System Aggregated by VSC-HVDC

Nowadays the first four terminals VSC-HVDC grid project in the world is building in North China. Two sending isolated island systems are consist of millions of kilowatts renewable energy and single converter station. Their reactive power and voltage control faces challenge. Aiming at this, this paper proposes a comprehensive voltage control strategy for renewable energy isolated island system aggregated by VSC-HVDC. The control strategy includes steady state voltage control and emergency voltage modulation. For steady state voltage control, the voltage control is achieved through a multi-objective optimization strategy considering the network loss and the reactive power margin of the sending terminal VSC station. An improved genetic algorithm is used to solve the optimization problem. For emergency voltage modulation, reactive power and voltage droop modulation is applied to the sending terminal converter. Case study shows that the strategy takes into account the safety and economic operation of island system and maintains the reactive power of sending terminal VSC converter within the safe operation range as well.